Universal equinoctial dial for latitudes 0°-85° North. This ivory dial consists of a universal equinoctial dial, compass and a table of latitudes. The dial is split up into four leaves. Leaf Ia features an equinoctial dial with the centre cut away to allow the rotation of the gnomon to the perpendicular. The gnomon is double-ended and is supported by a silver crossbar. Leaf Ib forms the underside of the equinoctial dial. It has an hour-circle, and a groove in the left hand side contains a strut for adjusting the angle of the dial for the latitude. The compass is set into leaf IIa, with a compass card mounted on a pivot. Set around it is a circular table for calculating the date of the new moon. Leaf IIb displays a table of latitudes for places in South America. On the front and right-hand side of the dial is a table for calculating the time of high tide.

The style of engraving indicates a South German origin for this instrument, quite possibly in Nuremberg. The dial was obviously intended for use in the Spanish colonies of South America, since the places listed in the latitude table are all in these areas. The table around the compass can be used to find the lunar age from the date. Used in conjunction with the tide table, it is then possible to calculate high tide for any day of the year. A very similar instrument is in the MHS, Oxford (new inventory no. 75822).

For more information regarding this dial please refer to the OUP & NMM catalogue, 'Sundials at Greenwich'.